Spectrum Controls 1769sc-IF8u - Manual (Page 14)

4 Compact IO ™ Universal Input module
8b lower DIN rail latch
9 write-on label for user identification tags
10 removable terminal block (RTB) with finger-safe cover
10a RTB upper retaining screw
10b RTB lower retaining screw
11 CJC sensor
General Diagnostic Features
The module contains a diagnostic LED that helps you identify the source
of problems that may occur during power-up or during normal channel
operation. The LED indicates both status and power. Power-up and
channel diagnostics are explained in Chapter 5, Diagnostics and
Troubleshooting.
S y s t e m S y s t e m S y s t e m S y s t e m S y s t e m
O v O v O v O v O v e r e r e r e r e r v i e v i e v i e v i e v i e w w w w w
The modules communicate to the controller through the bus interface. The
modules also receive 5 and 24V dc power through the bus interface.
System Operation
At power-up, the module performs a check of its internal circuits, memory,
and basic functions. During this time, the module status LED remains off.
If no faults are found during power-up diagnostics, the module status LED
is turned on.
After power-up checks are complete, the module waits for valid channel
configuration data. If an invalid configuration is detected, the module
generates a configuration error. Once a channel is properly configured and
enabled, it continuously converts the input data to a value within the range
selected for that channel.
Each time a channel is read by the input module, that data value is tested
by the module for an over-range, under-range, open-circuit, or “input data
not valid” condition. If such a condition is detected, a unique bit is set in
the channel status word. The channel status word is described in the Input
Data File in chapter 4.
Using the module image table, the controller reads the two’s complement
binary converted input data from the module. This typically occurs at the
end of the program scan or when commanded by the control program. If
the controller and the module determine that the data transfer has been
made without error, the data is used in the control program.